As a disk device, a magnetic disk drive comprises a housing including a base and an outer cover, and a rotatable magnetic disk and an actuator supporting a magnetic head are provided in the housing. As a method of improving the performance of the disk drive, a method of reducing airflow disturbance that affects the magnetic disk and the magnetic head, by sealing low-density gas such as helium in the housing, has been proposed.
In such a magnetic disk drive, by structuring the housing to be hermetically closed by laser welding the outer cover to the base of the housing, airtightness of the housing is increased. The laser welding is performed along the entire outer periphery of the outer cover. When a pressure in the housing is different from a pressure of the use environment of the magnetic disk drive, the outer cover, for example, may be deformed.